# NOT RUN {
data(simulations)
# Plot the second environmental surface: negative values as open circles and
# positive as solid black circles. Size proportional to absolute value
plot(simul.env[,1:2], pch=1, cex=simul.env[,4]/5)
points(simul.env[,1:2], pch=16, cex=-simul.env[,4]/5)
# }
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